The present invention concerns systems for deployment of air bags during vehicle crashes. More particularly it concerns systems in which the system operation is affected not only by information about the deceleration of the vehicle caused by crash forces, but also measured data concerning the passenger, including height, position and motion of the passenger, so that the system will operate in a manner to minimize the risk of serious injury to the passenger. It is also concerned with means to warn the passenger about the enhanced risk of serious injury which can occur during air bag deployment if the passenger is out of proper position in relation to the air bag system, and means to automatically release the passenger from the air bag restraint and regain passenger visibility when the collision is over.
Automobile air bag systems are a well known means of attempting to reduce the likelihood of serious injury to passengers in collisions. These systems are designed to very quickly inflate an air bag in front of a passenger during a collision, so as to hopefully prevent the passenger from colliding with hard objects in the passenger compartment interior, particularly the steering column and/or the dashboard. As described in documents filed with applicant's Information Disclosure Statement, the system typically senses that the vehicle is involved in a collision, by using an accelerometer to sense sudden deceleration of the vehicle. Rapid inflation of the air bag may be obtained by electrical ignition of a pyrotechnic substance which rapidly generates a volume of gas sufficient to inflate the air bag, or by means of compressed gas stored in a chamber which is part of the air bag system.
The performance of an air bag system, in terms of its success or failure in preventing serious passenger injury, may be critically dependent on facts concerning the initial position and subsequent motion of the passenger, which are not made known to the system by an accelerometer which senses deceleration of the vehicle as a whole. For example, if the passenger is seated too far forward, occupying the space into which the air bag will deploy, the passenger may, ironically, be seriously injured by the deployment of the air bag intended to prevent passenger injury. So there is clearly a need for passenger position sensing apparatus, which can prevent air bag deployment when the passenger is already too far forward when the collision begins.
But even if the passenger is not too far forward at the beginning of the collision, the passenger will tend to move rapidly forward, relative to the vehicle, as the vehicle rapidly decelerates, and will tend to move into the air bag deployment space, at least in the case of forward collisions, and may be too far into the air bag deployment space, before the completion of air bag deployment, to escape injury from the air bag deployment. There are a number of factors which may strongly influence the forward motion of the passenger, in addition to initial position. The relative forward motion of the passenger will depend strongly on whether the passenger has secured a seat lap belt and/or shoulder harness prior to the collision. The passenger's motion may also be influenced somewhat by the strength of any tensing up reaction the passenger has to the collision, i.e. instinctively pushing forward with the feet against the floorboard to restrain forward motion of the body. Such a protective reaction may vary greatly from one passenger to another, and may be greatly reduced or wholly absent if the collision is too sudden, so that the passenger has no time to react, or if the passenger is quite intoxicated. Also variation of the crash intensity by itself will cause considerable variation in passenger acceleration. So there is a need for systems which measure the position vs. time of the passenger, and analyze that information in making the yes or no decision on air bag deployment. Although such systems are known, as described in documents filed with applicant's Information Disclosure Statement, applicant is not aware of such a system employing overhead sensors, as in the present invention. Overhead sensors offer an advantage over those previously known systems having sensors located in front of the passenger, as in air bag systems and sensors mounted on the steering column, for which the sensors will at times by blocked from operating by the hands and/or forearms of the driver. Also such systems may not measure the change of position of most critical body parts, such as the head, but rather less critical portions, such as the torso.
The prospect for successful operation of an air bag system in a particular crash may depend not only on the passenger's initial position, and the motion of the passenger's body as a whole, but may also depend on the height of the passenger, which affects the position and motion of the passenger's head during the collision. The head of the passenger is of course particularly vulnerable to serious and often fatal injury from collision with hard surfaces during a collision. So the present invention includes sensor means to determine the height of the passenger's head, as one important initial position parameter to be considered by the system's microprocessor.
In order to discourage a passenger from riding in a position causing an increased risk of injury, such as a position too far forward, it is desirable to warn the passenger against such unsafe positions. It has been known to have a warning light for this purpose, where a position sensor detects this condition. However, a warning light alone may not be noticed, and the present invention also provides an additional means, for the driver, namely a tactile and printed warning sleeve on the steering wheel.
It is also desirable to have a means for the air bag to be automatically released after the collision is over, so that the bag can deflate and free the passenger to see and be able to bring the vehicle to a stop if it is still in motion, and be able to exit the vehicle and/or render aid to other passengers. This could be particularly important if another passenger is more seriously injured and needs immediate emergency rescue personnel to be called to the accident scene, or if a fire has started as a result of the collision. The present invention meets this need by providing an air bag release means which functions automatically.
Since the design of automotive air bag systems continues to evolve, as more knowledge is gained about the dynamics of crashes, including problems associated with variations in passenger motion during a crash, there is a need, for crash investigation purposes, for a system which can record the vehicle and passenger motion during the crash process. This need is met by the present invention, through the provision of recording means connected to the sensors which detect vehicle and passenger motion.
Depending upon the nature of the collision, there may be a need for an air bag in which the total cushioning time can be stretched out, to a longer time than that which could be obtained with a single chamber air bag. Applicant believes that the present invention may be useful in this respect, through the provision of a multichamber air bag, in which the gas flows sequentially between various chambers of the air bag.